Nuclear magnetic resonance (NMR) measuring apparatuses and electron spin resonance (ESR) measuring apparatuses are conventionally known as representative magnetic resonance measuring apparatuses. Magnetic resonance imaging (MRI) apparatuses are known as being similar to the NMR measuring apparatuses. Hereinafter, the NMR measuring apparatus will be described in detail below.
NMR is a phenomenon caused by atomic nuclei placed in a static magnetic field that interact with electromagnetic waves of specific frequencies. The NMR measuring apparatus is an apparatus capable of utilizing such a phenomenon to measure a sample at the atomic level. The NMR measuring apparatus can be practically used in analyses of organic compounds (e.g., chemicals and pesticides), high polymer materials (e.g., vinyl and polyethylene), and biological materials (e.g., nucleic acids and proteins). For example, the NMR measuring apparatus enables a user to examine the molecular structure of a sample.
The NMR apparatus includes an NMR probe (i.e., a probe for NMR signal detection) placed together with a sample in a superconducting magnet that generates a static magnetic field. The NMR probe includes a detection coil for transmission and reception. The detection coil has a function of applying a variable magnetic field to the sample in a transmission state and a function of receiving an NMR signal from the sample in a reception state. The resonance frequency is variable depending on an observation target nuclide. Therefore, in the measurement of the sample, a high-frequency signal having a particular frequency adapted to the observation target nuclide is given to the coil.
By the way, the surface resistance of a superconductor thin film is approximately two or three orders of magnitude lower than that of a normally conductive metal. Therefore, it is expected that the measurement sensitivity can be improved and the measurement time can be shortened if the detection coil is made of a superconductor. Further, the surface resistance of the superconductor thin film can be lowered in the magnetic field by introducing artificial pins (which may be referred to as “pinning centers”) in the superconductor thin film. The artificial pins are, for example, lattice defects, oxide fine particles, and the like, which do not interact with an intersecting magnetic flux in such a way as to keep the magnetic flux away. Introducing the artificial pins in the superconductive detection coil enables the magnetic flux to enter the artificial pins in the magnetic field. Therefore, the surface resistance of the detection coil can be lowered and the detection sensitivity can be improved.
As discussed in Japanese Patent Application Laid-Open No. 2013-140128, it is conventionally known that artificial pins can be formed in a superconductor by irradiating the superconductor with heavy ions.
As discussed in Japanese Patent Application Laid-Open No. 2012-199235, it is conventionally known that artificial pins can be formed in a superconductive thin film by irradiating the superconductive thin film with argon ions.
As discussed in Japanese Patent Application Laid-Open No. 2013-100218, it is conventionally known that artificial pins can be formed in a superconductive film by irradiating the superconductive film with ions.
When artificial pins are formed in a superconductor, it is usually difficult to finely process the superconductor. Therefore, it is difficult to process the superconductor including the artificial pins formed therein into a detection coil having a desired shape.
The present disclosure relates to a method for manufacturing a detection coil made of a superconductor and usable for magnetic resonance measurement, and the present disclosure intends to manufacture a detection coil having a lower surface resistance in the magnetic field and facilitate the processing into a desired shape of the detection coil.